Thermotropic liquid-crystalline polyester resin (which is called liquid-crystalline polyester resin or LCP hereinafter) is used not only for molded articles but also for a variety of products such as fibers and films because of its good properties including heat resistance, mechanical properties such as rigidity, chemical resistance and dimensional accuracy. Particularly, parts used in personal computers and mobile phones are highly integrated and the art wishes to use downsized, thinner and smaller parts. In the information and telecommunication fields, very thin parts, as thin as 0.5 mm or less of the thickness, are sometimes required. Based on the excellent molding properties of the LCPs including good flowability and less flash development compared to the other thermoplastic resins, consumption of the LCPs has been increasing.
On the other hand, there still exists a need for improving flowability, heat resistance and mechanical properties of liquid-crystalline polyester resins and there have been many proposals about the improvement of LCP. For example Japanese Patent Application Laid Open No. 511573/1996 discloses a liquid-crystalline polyester resin composition with improved heat resistance made by admixing an alkaline metal within certain kinds of monomers and polymerizing them.
However there is still a room for improvement with respect to uniform colorability and restoring the color of colorant such as carbon black, azo pigment and the like. Accordingly, in the field that requires uniform colorability and bright coloration, the use of LCP has been limited.
An object of the present invention is to provide a liquid-crystalline polyester resin with good colorability, an improved heat resistance and satisfactory mechanical properties.